Do you think it is alright for a girl to try to win a race for a bike ride explain your answers

Which characteristic accounts for the fact that red lights in dark rooms and DO NOT expose negatives during developing?

Marianna [84]

Answer:

the long wavelength and not focused on the negatives.

7 0

3 years ago

A 2.6 mm -diameter sphere is charged to -4.5 nC . An electron fired directly at the sphere from far away comes to within 0.37 mm

motikmotik

Answer: $1.96\times 10^{8}\ m/s$

Explanation:

Given

Diameter of sphere is $d=2.6\ mm\quad \quad[r=1.3 mm]$

Charge on the sphere is $Q=-4.5\ nC$

Nearest distance electron can reach to sphere is $d=0.37\ mm$

Here, kinetic energy of electron is converted into electrostatic energy between the two i.e.

$\Rightarrow \dfrac{1}{2}mv^2=\dfrac{kQq}{d}\\\\\Rightarrow \dfrac{1}{2}\times 9.1\times 10^{-31}\times v^2=\dfrac{9\times 10^9\times 4.5\times 10^{-9}\times 1.6\times 10^{-19}}{(3.7\times 10^{-4})}\\\\\Rightarrow v^2=3.8491\times 10^{16}\\\Rightarrow v=1.96\times 10^{8}\ m/s$

Thus, the initial speed of electron is $1.96\times 10^{8}\ m/s$ .

7 0

3 years ago

What is the initial velocity of a projectile that is launched at a 25o angle and travles 70 km in 25 seconds?

Novay_Z [31]

Answer: The initial velocity of the projectile is 3.1 km/s

Explanation:

There is a problem with the question because we do not know in which direction the projectile travels 70 km.

I will assume that the projectile travels 70 km horizontally, as is the usual case.

I will also assume that 25 seconds after the projectile is fired, it hits the ground.

Suppose that the initial velocity of the projectile is V0, and this velocity V0 can be thought as the hypotenuse of a triangle rectangle, then the x-component and the y-component of the velocity will be the catheti of this triangle rectangle, then we can write:

Vy = V0*sin(25°)

Vx = V0*cos(25°).

Now, the vertical problem does not affect the horizontal one, so we can see only the horizontal case.

Here we don't have any force, then there is no acceleration, then the velocity is constant and it is equal to:

v(t) = V0*cos(25°)

For the horizontal position we can integrate over time to get:

p(t) = V0*cos(25°)*t + p0

where p0 is the initial position, and we can assume that it is equal to zero.

Then:

p(t) = V0*cos(25°)*t

Now we know that in t = 25s, the position is 70km

(because the projectile travelled 70km in 25 seconds) then:

p(25s) = 70km = V0*cos(25°)*25s

Now we can solve this for V0.

V0 = 70km/(cos(25°)*25s) = 3.1 km/s

The initial velocity of the projectile is 3.1 km/s

The thing you can get from this is that we can analyze the vertical problem and the horizontal problem separately (for example, here we only solved the horizontal case and we ignored the vertical one).

4 0

3 years ago

A car is able to stop with an acceleration of − 3.00 m/s^2. Justify the mathematical routine used to calculate the distance requ

Gnesinka [82]

Answer:

129 m because the average velocity is 13.9 m/s, the change in velocity

divided by the acceleration is the time, and the time multiplied by the

average velocity is the distance. ⇒ answer C

Explanation:

Lets explain how to solve the problem

The given is:

The care is able to stop with an acceleration of -3 m/s²

→ The final velocity = 0 and acceleration = -3 m/s²

Calculate the distance required to stop from a velocity of 100 km/h

→ Initial velocity = 100 km/h

At first we must to change the unite of the initial velocity from km/h

to m/s because the units of the acceleration is m/s²

→ 1 km = 1000 meters and 1 hr = 3600 seconds

→ 100 km/h = (100 × 1000) ÷ 3600 = 27.78 m/s

The initial velocity is 27.78 m/s

Acceleration is the rate of change of velocity during the time,

then the time is the change of velocity divided by the acceleration

→ $t=\frac{v-u}{a}$

where v is the final velocity, u is the initial velocity, t is the time and

a is the acceleration

→ v = 0 , u = 27.78 m/s , a = -3 m/s²

Substitute these values in the rule

→ $t=\frac{0-27.78}{-3}=9.26$ seconds

The time to required stop is 9.26 seconds

We can calculate the distance by using the rule:

→ s = ut + $\frac{1}{2}$ at²

→ u = 27.78 m/s , t = 9.26 s , a = -3 m/s²

Substitute these values in the rule

→ s = 27.78(9.26) + $\frac{1}{2}$ (-3)(9.26) = 128.6 ≅ 129 m

The distance required to stop is 129 m

Average velocity is total distance divided by total time

→ Total distance = 129 m and total time = 9.26 s

→ average velocity = 129 ÷ 9.26 = 13.9 m/s

The average velocity is 13.9 m/s

So the time multiplied by the average velocity is the distance

The answer is C

129 m because the average velocity is 13.9 m/s, the change in

velocity divided by the acceleration is the time, and the time

by the average velocity is the distance.

7 0

3 years ago

A gas is quickly compressed in an isolated environment. During the event, the gas exchanged no heat with its surroundings. This

Olenka [21]

A gas is quickly compressed in isolated environment during the event,the gas exchanged no heat with its surroundings this process is adiabatic.

what is adiabatic process?

In thermodynamics,an adiabatic process is a type of the thermodynamic process that occurs without transferring heat or mass between a thermodynamic system and it's surroundings.

In an adiabatic process,in contrast to an isothermal process energy is only released into the environment as work.It is one of the effective applications of the adiabatic process. An example is a pendulum swinging in a vertical plane.

A quantum harmonic oscillator is also an example of an adiabatic system.

If you put ice in the icebox,it will not heat up and it will not heat up either.

learn more about adiabatic process from here: brainly.com/question/28197467

#SPJ4

4 0

1 year ago